


Hints on 
Painting 
Structural 
Steel. 




HINTS 



ON 



Painting Structural Steel 



AND NOTES ON PROMINENT 



PAINT MATERIALS 



Hj 4th Edition M' 



A Handbook for Paint-Users 

By HOUSTON LOWE 



1905 

THS LOWE BROTHERS COMPANY 

DAYTON, OHIO 



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Copyright, 1905 

THE LOWE BROTHERS COMPANY 

Dayton New York Chicago 
Kansas City 



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INTRODUCTION 

To First Edition 

ABOUT thirty years ago practice in the making of 
lyinseed Oil, Varnishes, Japans, and Colors first 
brought the writer into daily contact with questions re- 
garding the manipulation of paint, its properties, and the 
results of the various operations to which it was sub- 
jected. Painters, engineers, architects, builders, con- 
structors, etc., have since been continuously asking 
questions whose answers involved thought and experi- 
ment. 

At one time paintmaking was an art, then it became 
a trick, now it is a science. This little handbook is writ- 
ten by a paintmaker, and is the direct result of study 
recently given to the manufacture and properties of 
structural steel and the use of paint in its preservation. 
It is published in the hope that some of the mysteries 
heretofore associated with the paint business may be 
cleared up. 

Dayton, O., 1899. 



INTRODUCTION 

To the Fourth Edition 

SINCE the first edition of this book the writer has 
continued his observations, experiments, and tests 
on a more elaborate scale than ever before, assisted by 
his colleagues, Mr. John R. Dempsey (Painter) and Mr. 
Donald A. Kohr (Chemist), to whom he hereby makes 
grateful acknowledgment. 

Increasing knowledge and experience have served to 
strengthen his faith in the hypothesis under which he has 
been working. 

April 1, 1905. 



HYPOTHESIS 

" The earth hath bubbles, as the water has, and these are of them." 

— Shakspere. 

SUBSTANTIAL progress in any science is impossible 
in the absence of a working hypothesis, which is 
universal in its application to the phenomena pertaining 
to the subject matter." 

Paintmaking has been rescued from the domain of em- 
piricism and has become an exact science. One skilled 
in it can now practice it with a certainty of results, in 
an exact proportion to his knowledge of its principles, and 
to his ability in applying them to work in hand. 

The theory that oil, or the binder, is the life of Paint, 
that is, the thing that makes it wear, is misleading, and 
has been the cause of most of the blunders and failures 
with it in the past. An excess of linseed oil in paint is as 
much an adulteration of paint as the introduction of a 
useless or harmful pigment. We work upon the hypo- 
thesis that the solids are coefficient with the liquids in 
producing the best materials, and that the secret, if there 
be any, lies in the proper adjustment or determination of 
the amount and kind of each needed to secure a perfect 
product. No amount of theoretical and empirical knowl- 
edge can determine questions of this kind. There are 
to-day many signs, however, that in the struggle for 
victory men are accepting the logical conclusion from 
classified facts, their mutual relations and sequences, 
that properly prepared paint is bound to win out, because 
it is based upon ' 'sound idealism. ' ' The ' 'crude material- 
ism" of the advocates and exploiters of this, that, and the 
other "pure" pigment or binder, is but a relic of past 
ignorance, or worse, and is doomed to lose its force and to 
find its proper place. 

5 



PAINT AND PAINTING 

" Blind fear that seeing reason leads, finds safer footing than blind 

reason stumbling without fear." 

— Shakspere. 

PAINT 

" Give it to me to use ! I mix it with two in my thought." 

— Browning. 

PAINT is pigment plus binder, plus paintmaker. 
Paints for steel may be divided into three general 
classes, namely, Oil Paints, Varnish or Resin Paints, and 
Tar Paints. 

We are now treating of Oil Paints, that is, pigment 
mixed and mulled with oil, and especially designed to 
preserve, to protect, and to better the appearance of sur- 
faces to which they are applied. 

In Oil Paints of value the end aimed at is a close union 
of solids or pigment and liquids or binder, i. e., we take 
inorganic or solid matter in a finely divided state and mix 
with it organic or liquid matter, and then try to link them 
together either mechanically or chemically. Ordinary 
mechanical mixtures in which the solids and liquids have 
little or no afiinity for each other, or in which the powders 
are feebly suspended in the liquid, scarcely deserve the 
name of paint. 

The essentials of a preservative and protective covering 
for structural steel may be stated as follows : 

I. Mechanical properties. That it must work 
properly, that is, offer but a slight resistance to the stroke 
of the brush, and be of such fluid nature as to flow to- 



8 A Handbook for Paint-Users 

gether after the brush so that the resulting covering or 
skin is one of even thickness. 

II. Chemical properties. That it must not only 
dry, or oxidize, fast enough, but dry simultaneously 
throughout; not harden on the surface and remain soft 
underneath, or in painters' parlance, "skin over." 

III. Physical properties. 

( 1 ) Hardness. That it must be of such nature that 
when it has formed a skin upon the surface of 
the metal it can take other coats of paint without 
softening under them. 

(2) hidesiructibility . That it must wear well, pro- 
vided a sufficient number of coatings of it is 
applied. 

(3) Impenetrability. That it must exclude moisture 
from the metal covered with it, i. e., prevent 
its corrosion. 

How best to secure these essential features is a problem 
which has puzzled the heads and vexed the hearts of 
painters, chemists, and engineers for years, and it will 
probably continue to do so for years to come or until some 
means are devised under which it will be possible to 
determine quickly that coatings satisfy the requirements 
of service and use. As manufacturers of both oil and 
varnish paints, our faith is, at the present writing, estab- 
lished in oil paints, because years of study, observation, 
and experience have demonstrated their superiority for 
steel, if well made, to coatings of any other kind. 

From "sense impressions," gained by study of the 
phenomena pertaining to paint, both wet and dry, our 
present conception is that pigment is the objective element 
and liquid the subjective element in it. The pigment is 
the male principle ; liquid, the female. In order to give 



A Handbook for Paint-Users 9 

expression to our thoughts upon this question, it appears 
necessary to consider the nature of linseed oil. Many- 
books have been written upon this subject and there is 
yet much to learn. I^inseed oil, even if of good quality, 
is not sacred, but, after centuries of use, it still holds its 
own as the best oil for painters' use where durability 
is the main consideration. 

Ivinseed oil in drying changes from a liquid, first into 
a sort of jelly and then to a solid, rubber-like substance, 
which not only holds itself together, but also clings to any 
dry substance upon which it is formed. Linseed oil in dry- 
ing takes something from the air, namely, oxygen, and 
gives off something to the air, namely, carbon-dioxide and 
water. Mulder beautifully describes the process and calls 
it "the breathing of the drying oils." In his book, 
"Die Chemie der Austrocknenden Oele^ he named the 
solid, rubber-like substance into which a layer of linseed 
oil finally hardens, "linoxyn." Linoxyn is a solid, not a 
liquid. It is insoluble in many liquids and is far less 
soluble in any solvent than linseed oil. We have had 
specimens of it for months in dilute acid and weak alka- 
line solutions ; also in spirits of turpentine, petroleum 
naptha, linseed oil, alcohol, chloroform, acetone, carbon- 
bisulphide, and water, and in most of these liquids we 
find but slight decomposition or solution of it. These 
experiments indicate its power of resistance to atmos- 
pheric influences. 

A layer of dried linseed oil (linoxyn) is not waterproof, 
although no compound is probably chemically more re- 
sistant to atmospheric influences (not mechanical wear). 
For example, it is claimed that a gallon of oil spread upon 
one hundred square feet of surface will outwear a gallon 
of any paint spread upon the same area of a similar sur- 
face ; but it may be noted that it will require about three 



10 A Handbook for Paint-Users 

times as many coatings of the oil to use up the gallon as 
it will of the paint to use it up. From this we conclude 
that a layer of the paint is about three times as thick as 
a layer of the oil. Experiments of this kind demonstrate 
that one of the functions of pigment is to increase the 
thickness of the layer of dried paint, and that this in- 
crease of thickness is in direct proportion to the volume 
or fineness of the pigment. They also determine that, 
given the same volume of oil and the same weight of pig- 
ment — the greater the volume of the latter, i. e. , the finer 
the division of its particles — the more slowly will the 
paint dry and the longer will it wear. 

Pigments fit for use in structural oil paints are of two 
general classes, viz., those that react more or less with 
the oil, notably the carbonates and all of the lead pig- 
ments, and those that have no chemical action on the oil 
or binder, i. e., that are called inert, such as the carbons, 
silicates, probably ferric oxides, etc. The former class 
produce the quicker drying and the less durable paints ; 
the latter, the slower drying and the more durable coat- 
ings; e. g. , a paint made from White Lead and linseed oil 
when properly applied to a sound surface cannot be ex- 
pected to protect it, under fair conditions, more than five 
or six years, while a paint made from "Venetian" Red 
and the same oil, applied to a like surface under similar 
conditions, will protect it easily twice as long. The ob- 
server will note this if he will recall his observations of 
the durability of paint made from ordinary mineral colors 
on barns or freight cars, as compared with the more deli- 
cate tints used on houses and more elaborate structures. 
Another feature of interest pertaining to inert pigments 
is, that where the same liquids are used with them for the 
paint for each coating applied, the observer finds that the 
dried paint seldom cracks, peels or blisters, and if it does 



A Handbook, for Paint-Users 11 

the inference should be that his paint contained an inade- 
quate amount of pigment. Given a perfect binder, the 
paint problem would be simple and the only function of 
pigment would be to color and obscure the surface ; then 
the hypothesis under which we are working would fall. 
Until, however, a binder is obtained that will dry fast 
enough, that when dry is impervious to moisture and 
gases, and that will not wear out, pigment will be neces- 
sary to shield and to protect the dried oil from the agen- 
cies that destroy it, the chief of which are rainwater and 
sunshine. 

A pigment that will not hold the oil produces a fugitive 
paint. Any pigment that will take and retain oil or bind- 
ing material, and that is not changed by the agencies that 
destroy dried oil, or the binder, will make a durable paint 
for structural steel provided it is fairly treated and prop- 
erly applied to a surface in fit condition to receive paint. 

The decay of paint is due to chemical change, and 
nearly all chemical reactions are accelerated by water and 
heat. It is therefore necessary in designing protective 
coverings that materials be used which are repellent of 
moisture and as slightly affected by heat as possible. 

To understand the pigment question one needs some 
knowledge of forces which are insensible at sensible dis- 
tances, viz., molecular forces, such as surface attraction, 
chemical affinity, etc. All phenomena taking place in 
paint are due either to physical action (heat^ light, elec- 
tricity) or to chemical action, that is, the attractive or 
decomposing influence of one substance upon another. 

Andes in his work on Anti- Corrosive Paints, in discuss- 
ing the number of coats of oil paint that must be applied 
to iron in order to secure efficient protection against rust- 
ing, says that in establishing a standard, preference must 
undoubtedly be accorded to paints requiring a large pro- 



12 A Handbook for Paint-Users 

portion of oil to make them work properly. He says : 
"It may be laid down as a normal standard that, presup- 
posing the use of good paint, one bottoming coat and 
three subsequent coatings, laid on at suitable intervals, 
will be required to produce a layer of sufficient thickness 
on iron to keep moisture away from the metal and to pro- 
tect the latter from rust for a certain time." The first or 
prime coat upon a surface of steel, in a fit condition to 
receive paint, is of the greatest importance, especially as 
to its drying, hardening, adhesiveness and impermeability 
to water. 

We work upon the theory that the paint used for prim- 
ing naked steel should be of a preservative nature, i. e., 
of such a nature that it will absolutely exclude air and 
water from the metal, and that the finishing or top coats 
should be of a protective nature, i. e., of such nature 
that they will protect the primer or bottoming paint from 
the action of rainfall, sunshine or any special external 
condition. As the first or prime coat must form a recep- 
tive foundation that will be able to hold all subsequent or 
protective coatings both on and up, it should be largely 
formed of basic materials, so composed as to secure on the 
surface of the metal a firm and unyielding coating of an 
elastic, durable, cohesive and adhesive cement ; it is prob- 
ably necessary that this cement be made from a pigment 
that secures chemical action between itself and the liquid 
with which it is mixed, for it is only through the use of 
such a pigment that we can secure a skin or covering 
upon unheated metal that will be impervious to air and 
water. 

Theoretically, red lead in competent hands is the best 
pigment to use with linseed oil for making a primer for 
naked steel ; it forms a rapid-drying, firm, unyielding, 
impervious, non-corrosive and receptive covering upon 



A Handbook, for Paint- Users 13 

the metal, its only defect being that it will undergo chem- 
ical change when exposed to ordinary atmospheric condi- 
tions, therefore the necessity at all times of protecting the 
red lead with outer coatings of paint made from linseed 
oil and pigments that have no chemical action upon it, 
such as the carbons, ferric oxides, etc. ; that is, paint 
made from inert pigments. Red lead paint forms the 
best foundation. No one builds a stone house upon a 
wood foundation, but may build a wooden house upon a 
stone foundation. 

Unfortunately or otherwise, the cost of red lead, its 
great specific gravity or weight, the great fatigue attend- 
ant upon its proper application, the improbability of get- 
ting an even coating on the surface, its tendency to fatten 
or set, the trouble of mixing the dry pigment with the 
oil, its rapid settling when so mixed, and its poisonous 
nature, have prevented its adoption where its virtues have 
been acknowledged. False ideas of economy have too 
often been responsible for unwise attempts to preserve 
valuable structures with coverings made of inferior mate- 
rials, the only logical conclusion, that "the best is not 
good enough," being entirely lost sight of. 

As to the character of the pigments that should be used 
with linseed oil for making paint for use as top coats over 
a red lead primer, it is important that the pigments used 
be both chemically and physically inert, that they be in a 
finely divided state, and that they have an afiinity for lin- 
seed oil. Given these features, whether the pigment is 
Lamp Black, Graphite, Oxide of Iron, Charcoal, Silica, 
Mica, Aluminum, or what not, is a matter of little im- 
portance so far as durability is concerned. Where three 
or more coats are to be applied and it is not practicable to 
use more than two kinds of paint, we recommend for mid- 
dle coat mixtures of topping and bottoming coats. 



14 A Handbook for Paint-Users 

Paint-users have no just reason for condemning this, 
that, or the other pigment or binder, as tested upon any- 
given structure, unless they know, first, the history and 
characteristics of the material used ; second, the kind and 
condition of the surface to which it was applied ; and, 
third, the method of application. Many pigments, such 
as some kinds of red lead, iron oxide, carbon, white lead, 
etc., may give good results, if fairly treated, but if im- 
properly compounded and applied, prove failures. En- 
gineers, architects, etc., should demand paints that do not 
require great skill, and which do not involve great fatigue, 
in their proper application. 

A perfect paint for structural steel would be one in 
which the pigment (inorganic) and binder (organic) 
formed a close union (marriage), so that there could be 
no separation of them — no precipitation of the pigment. 
In other words, it would form and secure upon the surface 
of the metal an even covering of an adhesive, cohesive, 
elastic, harmless and durable cement, impervious to and 
unaffected by either moisture, sunlight or gases. The 
desired features of an anti-corrosive metal coating are, 
that it— 

1. Should hide the surface. 

2. Should cement itself together, and also cement 

itself to either damp or dry metallic surfaces. 

3. Should expand and contract without breaking its 

own body. 

4. Should present a hard, yet tough, outer surface. 

5. Should be impervious to water, marsh-gas or other 

gases. 

6. Should be unaffected by sunshine, heat, frost, dew 

or climatic changes. 



A Handbook for Paint-Users 15 

7. Should be unaffected by ordinary mechanical 

abrasion . 

8. Should wear evenly. 

9. Should fail by gradual wear, not by disintegration. 

10. Should leave a good surface for repainting. 

11. Should not require an unreasonable amount of 

skill or muscle in application. 

12. Should be homogeneous. 

13. Should dry fast enough. 

14. Should not be readily ignited. 

15. Should have power to extract moisture or damp- 

ness from the metal. 

Main causes for deterioration of paint : 

1. Water. (Dissolution.) 

2. Action of light and heat. (Chemical and physical 

change. ) 

3. Chemical action between pigment and binder. 

(Disintegration.) 

4. Abrasion or mechanical injury. (Motion.) 

5. Action of deleterious gases. (Foul air.) 

Why a worthy metal coating sometimes fails : 

1. Because of improper application. (Incompetent 

or careless users. ) 

2. Because of insufficient quantity on a given surface; 

not renewed at right time. (Perishes quickly.) 

3. Because of an unstable foundation to stick to. 

( Dirt, grease, dampness or scale under it.) 

4. Because the under-coating is more elastic than 

that over it. (Cracks.) 

5. Because not protected when drying. (Wet paint 

sensitive.) 



16 A Handbook for Paint-Users 

PAINTING 

" To be a painter have a heart and colors." 

— Miinkacsy. 

Painting is paint plus painter, plus the painter's em- 
ployee. It is possible to-day to get paint uniformly well 
prepared for almost any purpose. A painter or paint- 
user of the present time who attempts to mix and grind 
his own paints is as unlikely to succeed as if he were to 
attempt to make his own varnishes, brushes, etc. The 
coating of structural steel with paint is for the special 
purpose of preventing air and water from getting at it, as 
a combination of these will destroy steel, and that quickly 
if carbonic or some other acid be also present. It is not 
our purpose to suggest or discuss methods of applying 
coverings to structural steel other than to insist that a 
mechanic, to do good work, must have good tools to work 
with and fair conditions under which to do the work set 
before him. Many worthy paints are ruined because 
flowed on with a broad, thin, flat brush, not much better 
than a common whitewash brush, instead of being rubbed 
out and into the surface well with a good, full, round, 
bristle brush; and then, again, painters are apt, if the 
pigment used is heavy, or the parts to be covered are 
difficult of access, to add an excess of thinners to save 
labor or cost for material. A layer of air exists on all 
surfaces; hence the importance of rubbing out paint thor- 
oughly, as otherwise bubbles of air may be covered, 
which, coming through the paint, render the coating 
porous. It is known that the durability of any oil paint 
depends largely upon the number of particles of pigment 
upon a given area of surface, and that the more particles 
of pigment the better the protection to the binder and to 
the metal underneath; the evil of thinning too much is, 



A Handbook for Paint-Users 17 

therefore, obvious. As to the spraying of paiut upon 
structural steel by means of an air compressor, it is 
argued that this method conveys air and moisture to the 
metal and corrodes it; besides, its many other disadvan- 
tages have led to its abandonment wherever tried. The 
adherence of paint will be increased if the metal is moder- 
ately heated before it is primed, because if it is warmed by 
artificial heat, the surface will be dry. "Mill marks," 
even though made with inferior paiut, generally afford 
excellent protection to steel because the paint was applied 
to the metal when it was clean and warm. 

When painting is to be done in the field, or under con- 
ditions that make it impracticable to warm and dry the 
metal artificially, it is a good plan to apply paint heated 
to a temperature of about 150° F. , especially when the 
temperature of the atmosphere is below 55° F. This 
warming of paint may be attained by placing the pails of 
paint in vessels of hot water. It is important that one 
should always note the atmospheric conditions when the 
work of painting is being done. A temperature of about 
70° F. and an atmosphere that is free from moisture favor 
the right kind of drying. The humidity of the atmos- 
phere is even more important than its temperature. 
Nothing retards drying more than dampness and dark- 
ness. 

To aid in the inspection of new work, a shop coating of 
linseed oil is often specified. This does, in a measure, 
protect the iron from rust, but a very uneven film of dried 
oil will be probably secured from this method of treatment. 
Oil applied to a vertical surface runs off until the layer 
reaches a certain thickness. Where the current meets 
with an obstruction it piles up into a thick and uneven 
coating. These thick parts of the layer may require 
months to harden into a substance firm enough to be fit 



18 A Handbook for Paint-Users 

to paint over. The results are most disastrous in cold 
weather when oil thickens and contracts. As painters ex- 
press it, oil, when applied to cold steel, crawls, wrinkles, 
and crinkles. If linseed oil is used as a primer on steel, it 
should be used hot, not warm, then it will penetrate the 
skin of the metal and one may gain a thin and even film, 
hard enough to form a surface fit to receive paint. 

Many places, such as "the under and inner sides of 
girders, bolt heads and nuts, rivets, etc., which should be 
painted with great care to prevent the incursion of water, 
are often overlooked or neglected. To aid inspectors, a 
proper check upon the workmanship can be secured by 
selecting different colors for the several coatings, so that 
uncoated or defective places may be readily detected. ' ' — 
(^Andes.') 

A distinguished British painter and author writes : 
"The less paint that is put on at each operation, consist- 
ten tly with a proper covering of the ground, the better 
will the ultimate result be." "L,ess paint and more 
painting," he impresses as a need "to quite 90 per cent. 
of painter students." "The under coats should dry more 
quickly and be harder than those above them, and the 
difference in drying between two adjoining coats should 
not be very great. ' ' 

We have made numbers of experiments that give to us 
ocular demonstrations of the fact that a first coating of 
good Red-lead paint covered by a layer of good carbon or 
ferric oxide paint will prevent corrosion for a much 
greater period than two coatings of any one kind of paint. 

To secure durability with paint it should always be used 
fairly thick, and then well rubbed out under the brush 
into thin and even layers. If not well brushed it will 
lack firm adherence. From experiments with an ocular 
micrometer in connection with a microscope, we find that 



A Handbool^ for Paint-Users 19 

single coats of dried paint vary in thickness from ^-^ to 
Y^V(5" of 2in inch, the difference being due either to the 
manner of application, i. e., whether under light or heavy- 
pressure of the brush, or to the difference in the consist- 
ency of the paints tested. Few realize the thinness of 
coatings of paint or the strains to which its dried films are 
subjected. 

Viaducts, tunnels, crossing bridges, etc., require dif- 
ferent treatment from structures exposed chiefly to the 
action of rain-water and sunshine. lyinseed oil, in drying, 
as already explained, undergoes a metamorphosis; and the 
result of this process is a solid, linoxyn. A film of this 
dried linseed oil, or linoxyn, is not quickly formed without 
dry air and light, but once formed, is much more stable and 
better able to resist the agencies that destroy paint than 
a thin layer of undried linseed oil; in other words, wet 
paint is much more sensitive than dried paint. There- 
fore, in locations that are ill-ventilated, that get no sun- 
shine, that are damp and filled at times with steam and 
acid gases, one must have material of a different kind for 
coating steel. We have found varnish or resin paints 
best adapted to work of this kind, and especially so where 
a primer coating of Red-lead paint, so composed that it 
will dry rapidly, has been used. 

Much has been said and written of late regarding the 
apparent failure of paints of wide reputation when applied 
to steel cars. From a limited personal knowledge and 
from information gained from others who have handled 
thousands of hopper-bottom Gondolas and box cars with 
steel under frames, we are led to conclude that some con- 
tract shops use less of the paint specified than has been 
presumed. What they do use is frequently applied in the 
open under such unfavorable weather conditions, and 
under conditions of painting contracts at such a low rate 



20 A Handbook for Paint-Users 

per car, as to preclude the possibility of either employing 
competent workmen to apply the paint or such application 
of it as to prevent corrosion. Good paint illegitimately 
thinned with cheap oils or japans is practically rendered 
of little protective value, and to apply it to steel cars more 
or less covered with rolling-mill scale, dew, frost, snow, 
slush, ice, grease, etc., is waste of time, thought, and 
material. There is no reason why paint applied to steel 
cars should not wear as well as paint applied to any other 
steel structures, provided it is used under fair conditions, 
applied by competent workmen, and enough time for dry- 
ing is allowed to elapse between coatings. The only way 
to secure better painting is to employ competent and 
vigilant inspection of the painter's work. 

FACTORS THAT AFFECT RESULTS IN PAINTING. 

1st. Location of the structure, e. g., seaboard or 
inland. 

2d. Kind and condition of the surface. 

3d. Quality of the paint. 

4th. Workmanship of the painter. 

5th. Number of coats applied. 

6th. Time allowed to elapse between coats. 

7th. Atmospheric conditions when painting is done. 



STEEL. 

"This is the very petinting of your fear." 

STEEL is iron plus carbon and other impurities, plus 
metallurgists." Professor Henry M. Howe, in his 
recent work, "Iron, Steel and Other Alloys," writes in 
part as follows : 

"What are the iron and steel of commerce and indus- 
try? Examined under the microscope they prove to be 
composite or granitic substances, intimate mechanical 
mixtures or conglomerates of microscopic particles of cer- 
tain quite distinct, well defined, simple substances, in 
widely varying proportions. >!<*** 

' 'The chief of these substances are : 

1. Pure (or nearly pure) metallic iron called ferrite — 
soft, weak, and very ductile, * * * * 

2. A definite iron carbide called cementite, which is 
harder than glass and nearly as brittle. * * * * 

"Besides these two constituents of prime importance, 
there are three others of moment : 

3. Graphite — unimportant in steel, but important in 
gray cast iron. 

4. Slag — present in wrought iron. 

5. Austenite — Hardened steel : steel hardened by sud- 
den cooling from a red heat consists essentially of austen- 
ite, a solid solution of carbon in iron of varying degrees 
of concentration." 

Steel is usually divided into four general classes, name- 
ly. Converted or Cemented Steel, Crucible Cast Steel, 
Bessemer (acid or basic) Cast Steel, and Open-Hearth 
(acid or basic) Cast Steel. Our troubles and complaints 
come from structural (Bessemer and Open-Hearth) steel. 

21 



22 A Handbook for Paint-Users 

To know some of the causes for them, it is well to visit 
occasionally works where steel is made, to investigate 
modern methods of handling and treating it, and to talk 
with those whose lives have made them familiar with the 
ethics and practice of steel producers. 

It is not easy to-day for the uninformed to get sound, 
homogeneous, inert structural steel — that is, metal that 
is free from pipes, seams, water-cracks, blow-holes, dis- 
coloration, etc., or excess of oxygen or nitrogen, or is of 
fairly fine, even grain, elasticity, and hardness ; and when 
it may be had few are willing to pay for it. It is possibly 
wise to apply a cheap paint, or a tar preparation, to a sur- 
face of structural steel that is covered with scale, rust, 
grease, and dirt, as it frequently happens to be, when 
taken from the works or from the field to-day. Coatings 
of worthy paint upon such an unstable foundation are 
bound either to be decomposed or soon forced off the sur- 
face by the moisture, scale, or grease under them. 

Up to the present time no physical or chemical tests 
have been discovered that can distinguish between Bes- 
semer and Open-Hearth Steel, or between acid and basic, 
provided the same materials have been used in making 
them. This fact is ' 'so well known that some of the best 
and most careful engineers in the country, including those 
who are most stringent in their demands concerning phys- 
ical and chemical qualities, do not make any surface in- 
spection," and yet flaws, flash, rust, grease, and dirt in 
the surface, are things that may destroy the work of the 
painters. No surface of structural steel ought to be coated 
with paint, unless it shows the grayish- white, natural color 
of the metal. 

Now, it may be noted at times immediately after the 
removal of the scale from the surface of steel by means of 
a sand-blast, that the parts are soon covered with rust. In 



A Handbook for Paint-Users 23 

reply to a direct question of the author, Professor Henry 
M. Howe recently wrote : "The reason for this is that the 
sand-blast roughens the surface, and that on a rough sur- 
face of iron, as we all know, rust forms much more rapidly 
than on a smooth one. You can leave a razor lying in a 
drawer for years without its rusting at all, because it is so 
highly polished, whereas a piece of rough, unpolished steel 
lying beside it will rust very rapidly. 

' 'There is no doubt that the scale itself is in one sense 
a preventive against rusting ; that is, it adheres pretty 
closely to the skin of the metal and mechanically excludes 
the air. The scale itself is in most cases unoxidable ; it 
consists approximately of magnetic oxide, which is ex- 
tremely stable and resists oxidation. It is true that if 
part of the surface be covered with scale and the rest be 
naked, the naked part will rust more rapidly because of 
the presence of that scale on the neighboring parts, the 
scale acting 'by difference of potential,' as the electricians 
say. But so long as the scale is intact, it acts similarly 
to paint, excluding the air. ' ' The writer adds : "I do not 
know that I can fully suggest a remedy — the only thing 
that occurs to me as worth trying is to modify the sand- 
blast so as to reduce to a minimum its roughening effect, 
as, for instance, by using sand the grains of which are 
round instesid of skarp (and such sand can be found), or 
by using ^ne sand." 

Steel differs from wood, brick, etc., in that there is 
much less absorption of the paint into its body, so that 
the adhesion of the first or foundation coating of paint 
upon steel is necessarily almost wholly restricted to its 
surface, and the adhesion of subsequent coats is restricted 
to the surface of the dried paint already in position. "The 
better adhesion of paint to puddled iron than to steel can 
readily be accounted for by the greater roughness of the 



24 A Handbook for Paint- Users 

puddled iron, due to its containing a small quantity of 
cinder widely scattered throughout it in minute particles, 
whereas steel contains none. ' ' 

Steel is perhaps the most tenacious of all known sub- 
stances, — that is, tough, — having great cohesive force be- 
tween its particles, so that they resist any effort to pull or 
force them apart ; and as we fancy all matter to be in a 
state of motion at all times, the difficulty in preserving it 
by use of a paint is at once apparent. The defects in 
modern structural steel are largely due to its mechanical 
working — that is, it is run out too hot and too quick, and 
afterwards not properly housed and cared for. "The 
enormous increase of late in its use in building and en- 
gineering construction in various forms, demands increas- 
ing and vigilant attention to its maintenance and present 
condition, wherever it has been placed, as either from 
corrosion, fatigue, vibration, or general deterioration, the 
metal may become so impaired as to be unfit to do that for 
which it was designed." 



RUST 

" Sloth, like rust, consumes faster than labor wears ; 
while the used key is always bright." 

Rust is iron plus air and water, plus nature. It is 
formed by a solution of oxygen in water. Iron-rust does 
not protect steel from further attacks of rust-producing 
bodies. It is a loose and porous mass containing about 
20 per cent, of water, and it permits the passage of water 
and gases through itself to the metal underneath. 

This characteristic of rust to absorb and persistently re- 
tain water, which, in conjunction with atmospheric air, 
continuously corrodes such portions of the metal under- 



A Handbook for Paint-Users 25 

neath that remain intact, furnishes a reason for the com- 
plete corrosion of rivets and screws in steel structures. 

"Steel does not rust in dry air or in water free from air 
and carbon dioxide. The best protections will, therefore, 
be obtained from the most impervious coating. ' ' It may 
be noted that the general cause for the failure of oil paints 
to protect steel from rust, is that they are permeable to 
moist air and carbon dioxide, which are the general causes 
for the corrosion of the metal itself. 

"Sweat," the water of condensation, is always present 
on a surface of steel or iron when its temperature is lower 
than that of the surrounding atmosphere. "Simon made 
observations in the softening of paint by dew on the iron- 
work of bridges, the result being the formation of rust ; 
he expresses the opinion that rusting is not attributable 
to the iron's having been insufficiently cleansed before 
painting, but rather to the deposition of dew, the result 
being rapid cooling of the metal, the liquid being then 
absorbed by the paint and brought into contact with the 
iron, which is thereb}' rusted." 

Rust has a tendency to grow and spread out from a cen- 
ter ; hence a small spot of it on the metal may extend 
itself under the paint, so that in time the paint will be 
flaked off and the metal exposed. 

Some agencies for rapid corrosion : 

1 . Smoke and heated vapors issuing from locomotives. 

2. "Collection of soot, dust, or anything that will re- 

tain moisture in sheltered places," 

3. Alternate exposure to air and water. 

4. Exposure to acid or alkaline gases, vapors, or 

liquids. 

5. "Considerable and varying heat and cold." 



26 A Handbook for Paint-Users 

6. "Constant or alternately occurring heavy rains 

with drying winds, hot sun, frost, or snow." 

7. Heating apparatus in buildings causing damp 

places in walls. 

8. Brackish soil and sewage. 

9. Salt-water drippings from refrigerator cars. 

10. Damp, vitiated air in tunnels, subways, covered 

and confined places of all kinds. 

11. "Electrolytic action." 

12. Decaying animal or vegetable matter. 



CLEANING 

" I require a menial to clean it now and then." 

The cleaning of structural steel is a problem for en- 
gineers, and yet common sense tells us, as paintmakers, 
that heat of sufl&cient degree to evaporate any moisture 
that may be in contact with the metal, or to burn up any 
grease that may rest upon it, is, perhaps, the best method 
of preparing the surface of structural steel properly to 
receive a covering of paint. In repainting old structures, 
all dirt, loose scale, and dead paint should be removed 
with wire brushes or chisels made of old files, then all 
rusty places soaked with benzine, and a hot-blast blow- 
torch flame applied to burn out all the benzine, and to 
change the yellow (hydrated) oxide of iron to the red 
(anhydrous) oxide, which is inert and harmless. Objec- 
tion is made to this method of cleaning steel because of 
the expense of it. 

The sand-blast seems to offer the most rapid and eco- 
nomical means of preparing structural steel to receive a 
coating of paint. It leaves the metal not only clean, but 
fairly dry — an important and essential condition if a re- 



A Handbook for Paint-Users 27 

ceptive surface is to be secured. The painting of the 
metal should follow immediately after the cleaning is 
done, as cleaned metal will corrode under ordinary atmos- 
pheric conditions much more rapidly than uncleaned 
metal. It is argued that "aside from the chemical or 
scientific value of sand-blasting there is a very serious 
question of its effect upon the eyes and lungs of the 
operator." It is further argued that the sand-blast 
should not be used to clean new metal because it will re- 
move the sub-oxide, black oxide, or mill scale, which in 
itself, like paint, is a protection against rust formation so 
long as it remains. The sand-blast certainly offers the 
best means of cleaning old structures which are very 
rusty, and now that portable air compressors are avail- 
able, it is fair to presume that metal coatings will have 
better opportunities in the future to prove the life that is 
in them than they have had in the past. For an interest- 
ing paper on sand-blast cleaning of steel, with discussions 
by prominent engineers, the reader is referred to the 
"Transactions of the American Society of Civil Engi- 
neers," Vol. Iv, Paper No. 948. 

It is said that a thousand times as much iron and steel 
is cleaned by pickling as is cleaned by the sand-blast, e. 
g., all work that is to be electro-plated and all work to 
which a vitreous enamel is to be applied, such as granite 
earthenware, etc. Why more structural steel is not 
cleaned in this way we do not know, but it is well to re- 
member that pickling with hot dilute sulphuric acid or 
with hot muriatic acid should be avoided, unless one is 
well prepared to neutralize thoroughly and remove all 
traces of the acid from the metal immediately after it is 
taken from its bath. 



LIQUIDS AND SOLIDS 

Eligible for Use in Designing Metal Coverings 
LIQUIDS 

" How many fondly waste the studious hour, 
To seek in process what they want in power ; 
Till all in gums engross'd, Macgilps, and oils, 
The painter sinks amid the chemist's toils." 

— Shee. 

Linseed Oil. — First amongst the liquids used for paint- 
tnakiug stands a worthy quality of linseed oil, on account 
of its exclusive excellence — the fact that it is the best 
drying oil known, by reason of its nature and its great 
affinity for oxygen. 

There are many kinds of pure linseed oil made and sold 
to-day, and a guarantee of an oil's purity is no evidence 
of its quality or commercial value. One might classify 
the ' 'pure' ' linseed oil marketed as follows : Praise- 
worthy, fair, and unsatisfactory. 

A praiseworthy linseed oil will be of a pale yellow color, 
brilliant, limpid, drying well, with a rich luster, and hav- 
a pleasant, nutty taste. 

A fair linseed oil will be a yellowish oil, with a brown 
hue; clear, drying fairly; not very pleasant to the taste, 
but somewhat bitter. 

An unsatisfactory linseed oil will be of a greenish or 
dark color, uncertain taste, cloudy, and drying poorly. 

If all the liquid matter pressed out of flaxseed were 
painter's oil, and it were common to get a uniformly fair 
quality of it, substitutes for linseed could not be sold. 



A Handbook for Paint-Users 29 

Thirty years ago, one and one-half gallons of oil were con- 
sidered a fair yield from a bushel of flaxseed; to-day, with 
steam and hot pressure, two and one-half gallons are not 
enough to satisfy the sellers of the ' 'strictly pure. ' ' 

The quality of linseed oil depends as much upon the 
quality of the seeds from which it is made, as upon the 
manner in which the oil is expressed from the seeds, and 
upon the way in which it is afterwards stored and cared 
for. The seed of the flax plant is a laboratory in which 
we find working: 

1. Albumen (plant flesh), the growing principle. 

2. Mucilage, starch, and sugar as elements for nour- 

ishment. 

3. Oil, "which may be changed into sugar and starch 

and used as food. ' ' 

Time does not permit us to go into the effects of climate 
and soil upon the quality of the flaxseed; the ill effects of 
frost and excess of rain upon it; the good effects of age 
upon it (old seed better than new seed); nor into the 
quantities of foreign seeds, like those of the wild mustard, 
rape, and pigeon weeds, generally found associated with 
the flax plant. But to give an idea of the many kinds of 
flaxseed used by crushers, we would refer to "the regula- 
tions for the inspection of flaxseed, adopted by the Board 
of Directors and approved by the Board of Trade of the 
city of Chicago, to be in full force and effect on and after 
July 1st, A. D. 1899." 

Boiled Linseed Oil. — The author first boiled linseed oil 
in 1869. It was boiled in bulk in open kettles, holding 
1,000 gallons each, over an open fire, the pigment used as 
an oxidizing agent being either litharge or red lead. The 
heat was kept on the oil, until it was hot enough to scorch 
a feather or melt a piece of tin (good thermometers or py- 



30 A Handbook for Paint- Users 

roraeters v/ere not to be had then as now). Such boiled 
oil sold then for six cents per gallon over the price of raw 
linseed oil, and it would be worth at least that difference 
to-day for some purposes if it could be had. We know of 
no one that sells it, but we know of some old painters who 
have their own kettles and cook it. Boiled oil of this kind 
is rich in luster and body (a kind of varnish). 

Commercial boiled oil is an uncertain quantity. We 
know of no satisfactory chemical or mechanical tests that 
determine its quality. Experiment and observation have 
taught us that no treatment of flaxseed oil improves it 
like storage and repose in tanks under favorable condi- 
tions. Under unfavorable atmospheric conditions, raw oil 
in paint may be made to dry better and more rapidly than 
boiled oil. When blended with a japan or siccative of the 
right kind, well-settled raw oil dries simultaneously 
throughout. Boiled oil dries on the surface first, and 
therefore is more apt to crack. A fair quality of boiled 
oil is preferable to raw oil made from unripe or impure 
flaxseed, or to raw oil improperly treated. 

Linseed Oil Substitutes. — None of the standard litera- 
ture upon oils recognizes any animal, vegetable, or min- 
eral oil as the equal of linseed oil for painter's use. Some 
of them are valuable as thinners or extenders of it, 
improving both its working and drying properties, espe- 
cially if the linseed used be viscous. The base of the best 
substitutes for linseed oil is linseed oil itself. Various 
petroleum products of greater density than benzine are 
sometimes added to linseed oil, with or without other in- 
gredients, to form paint oils. These are merely physical 
mixtures, the un worthiness of which increases as the per- 
centage of linseed oil decreases. The non-drying and 
non-sticking properties of petroleum are so pronounced as 



A Handbook for Paint-Users 31 

to offset any virtue it may possess in offering resistance to 
atmospheric influences. 

Spirits of Turpentine is miscible with hnseed oil in any 
proportion. As a thinner, it ranks high; if of good qual- 
ity, it has a refreshing smell and will entirely evaporate; 
it improves the working and wearing property of paint un- 
der many circumstances, but diminishes its luster. Good 
spirits of turpentine is not difficult to obtain; when it has 
deteriorated by age its quality may be restored by redis- 
tillation. 

Petroleum Naphtha ("benzine") is very volatile and 
readily ignited; if free from impurities, like parafl&ne, 
glue, and water, its limited use, under certain conditions, 
is not objectionable, but advantageous, often indeed on 
account of its volatility. It also permits of the formation 
of a higher gloss in the dry paint coating than can be 
obtained when turpentine is used; and when old paint is 
to be covered, benzine in the coat applied will impart to 
it better cementing properties than will be imparted by 
spirits of turpentine. 

However, paints containing benzine tend to thicken up 
when allowed to stand open, due to evaporation of the 
light thinner. Other drawbacks to its use are its inflam- 
mable nature, and the fact that its low price may in many 
instances lead to its excessive use, in which case it is an 
injury to paint. 

Painters' Japans and Siccatives, or Driers. — Paints dry 
by evaporation and by oxidation. The function of driers 
of any kind is to increase the rate; they are usually made 
from lead or manganese oxides cooked in oil, and then re- 
duced with some solvent like spirits of turpentine or 
naphtha. Gum is frequently added to harden the oil. 
Gum causes the japan itself to dry more rapidly, but re- 



32 A Handbook for Paint-Users 

duces its power to dry oil paint. Present conditions often 
demand quick drying paint; in such cases use the best 
japan you can get, so that you will not shorten the life of 
your paint. The quality of a japan depends as much upon 
its cooking as upon the quality of the materials used in 
making it; too much heat or too long a heat frequently 
spoils it. It is not easy to enumerate all the possible ways 
in which a given number of things, like the ingredients of 
a painters' japan, may be mixed and combined together, 
nor the changes that may result from an excess of this or 
that component part, nor the degree or period of heat to 
which it is subjected. The only simple way that we can 
suggest to test the quality of a japan is to have a standard 
sample, whose efficiency has been proven, for comparison. 
A good japan is a painter's best friend, but it takes some 
little time and skill to determine its durability, drying, 
and binding properties. Concentrated dryers are obtained 
by heating linseed oil with excessive weights of lead and 
manganese oxides until the product becomes viscous, like 
sticking-plaster. Liquid driers are concentrated driers 
thinned out while hot with naphtha or spirits of turpen- 
tine; sometimes rosin or better resins are added to give 
viscosity. The function of painters' japans, etc., should 
be to "hurry up" the drying of the binder, yet the lower 
grades are often used as extenders or cheapeners. 

Metallic Soap. — The principal constituents of linseed 
oil (about 85 per cent.) are the glycerides linolein, lino- 
lenin, and isolinolenin. They are "esters of glycerine and 
linolic, linolenic, and isolenolenic acids;" and it is to them 
that the drying of linseed oil is due. These glycerides 
are very easily saponified. The soaps formed from them 
with potash, soda, or ammonia readily dissolve in water, 
but those containing lead, calcium, iron, zinc, or manga- 
nese as the base are more or less insoluble, and are usually 



A Handbook for Paint-Users 33 

known as metallic soaps. All japans embody the soap 
principle; and it is the soap principle in paint that gives 
linseed oil two of its most valuable properties; namely, 
rapid drying and easy flow. We claim that to day a 
satisfactory paint, for outdoor use, cannot be made unless 
it embodies the soap principle. The saponification will 
either result from the pigment proper or one or more of 
the elements of a pigment forced into the binder by heat, 

SOLIDS 

" Their time in envious search of colours lose, 
Which, when they find, they lack the skill to use." 

— S/iee. 

Carbo7is. — The prominent paint pigments of the carbon 
group are graphite and lamp-black, or soot. They depend 
for their coloring principle upon the carbon contained in 
them, and if well made, have no chemical action upon the 
liquid with which they are used. 

Graphite exists in two forms — * ' amorphous ' ' and 
crystalline, or fibrous. The crystalline form, 80-95 per 
cent, carbon, includes kinds called globular, granular, 
foliated, scaly, flake, etc. Any of these kinds is to a 
limited extent eligible for paintmaking, but the ' 'amor- 
phous" 80-90 per cent, carbon is generally conceded the 
best on account of its susceptibility to finer division. 
Much of the stuff sold as graphite is but a carbonaceous 
schist — that is, a kind of coal or slate. Genuine "amor- 
phous" or crystalline graphites do not make good paints; 
they are soft, unctuous, and greasy, and serve better as 
lubricators, but if compounded with a pigment or pig- 
ments that have aflinity for oil, Hke red lead, white lead, 
zinc, etc. , good results may be obtained from their use as 
an important component of paint. 



34 A Handbook for Paint-Users 

Spennrath says that he made his experiments with 
chemically pure graphite. We are not able to obtain 
"chemically pure" graphite at even $5.00 per pound. 

Electric graphite is now in very general use as a carbon 
pigment. It is made by heating anthracite coal to a very 
high temperature (as high as 6,000° F.) in an electric 
furnace. A graphite of very uniform and superior quality 
is obtained. It contains about 90 per cent, of carbon, and 
the remaining 10 per cent, consists of matter as inert as 
the graphite itself. 

Lamp-black — that is, soot or the black of smoke — 
represents almost pure carbon when prepared with proper 
care. The raw materials for its manufacture are numer- 
ous, including rosin, naphtha, coal tar products, tallow, 
or any oily substance which will burn with a smoky flame, 
provided its use is not prohibited by considerations of cost. 

These materials are burned according to their nature 
either in burners or heated kettles in such a manner as to 
produce a very smoky flame. This smoke is then col- 
lected in bags or chambers. 

L,amp-blacks are not changed by air or sunlight, and 
when well made are excellent pigments. 

Gas-black is the soot from the partial combustion of a 
hydrocarbon gas ; the pigment must be an impact black, 
free from grit and dirt. It is not suitable for mixing with 
white lead or zinc for making tints. 

Oxides of Iro7i. — Oxide of iron pigments are obtained 
from natural and artificial sources ; they vary largely in 
their characteristics, and in their chemical composition. 
Pigments of this class suitable for making paint may range 
from 98 per cent, down to as low as 10 per cent, of ferric 
oxide, their value as pigments depending less upon the 
amount of iron present than upon their physical proper- 



A HandbooJz for Paint-Users 35 

ties, and the composition of the material which is not 
oxide of iron. 

Roasted iron ores often yield excellent pigments, the 
quality depending upon the character of the ore, the con- 
struction of the furnace, the uniformity of the heat, and 
the care and attention given to the milling and grinding. 

Natural ores or mineral earths seldom yield pigments 
that are good for making metal coatings, for the reason 
that they contain more or less water, and are apt to con- 
tain sulphur or other unstable elements, one exception to 
this being the rich hematite ore from the I^ake Superior 
district. It yields a heavy pigment of value. One reason 
paint compounded from it wears so well is because of its 
specific gravity. It is almost a pure ferric oxide, and re- 
quires a small proportion of oil to prepare it for applica- 
tion in a paint. 

Artificial oxides of iron are sold under a variety of 
names, such as Indian, Turkey, Venetian red, etc. If 
properly made, some are stable pigments. They are made 
under a variety of processes, but usually by calcining 
copperas. Years ago, Venetian reds were burnt ochres, 
and, therefore, produced more durable paints than the 
copperas reds of the present day, which latter are apt to 
contain traces of sulphurous acid, and frequently excesses 
of land-plaster and powdered limestone. 

Lead Oxides. — Litharge is a heavy yellow powder fre- 
quently containing metallic lead and dirt. It is prepared 
by heating metallic lead or the dross from molten lead in 
an oven, through which is passed a current of air. 

Its value as a pigment is restricted, for unless used in 
proper combination with other pigments, its action on the 
oil may be so great as to shorten the life of the paint. 

Red Lead is formed by the continued heating of litharge 
in the air at 575°-750° F. Its quahty depends on the 



36 A Handbook for Paint-Users 

care and skill employed in its manufacture ; much of the 
commercial article contains metallic lead, vitrified particles 
and excessive amounts of litharge. 

Red lead contains more oxygen than does litharge, but 
for chemical reasons its action on linseed oil should be 
much less than that of litharge, when used with it in 
paint. Experience has shown this to be a fact, and has 
also demonstrated that a high grade of red lead is a valu- 
able pigment. 

Such a grade of red lead, when properly mixed for use, 
and applied to a smooth, vertical surface, should neither 
run, separate, nor sag. Red lead should be used as a 
plaster upon steel, not as a paint. We know of no first 
coating equal to it, for it forms a tough, adhesive, and 
unyielding cement, that not only dries well, but does not 
retard the drying of any paint spread over it. It is 
claimed that the fact that red lead sometimes hastens the 
drying of any paint spread over it is a reason for its con- 
demnation. It is true that if the red lead coat is not dry 
when it is painted over it will quickly oxidize or burn up 
the paint or varnish covering it ; but if the red lead 
priming coat is made to dry right, if hurried work is to 
be done, or if a mixture of it and raw linseed oil are 
allowed ample time to dry, then the paint topping it will 
be permitted to live out its natural life. Red lead plaster 
should always be protected by elastic coatings, the pig- 
ments largely composing which should have no chemical 
action on the binder. 

Orange mineral results from the calcination of white 
lead ; in the finished product the carbonic principle re- 
mains. It closely resembles red lead in composition and 
in its properties, but is more bulky and works better. Its 
use will probably increase. 



A Handbook for Paint- Users 37 

White Lead. — White Lead is the best white pigment 
with one base known to-day. It is popular with painters 
because of its working and drying properties, and because 
of its covering or hiding power. At best it is a soft, 
sensitive, and unstable compound, and often, as sold, it is 
but a mechanical mixture of White L,ead and other salts 
of lead that are white. Corroded lead is not amorphous, 
but exists in "rhombic cubes" of solid nature. 

White Lead is a mixture or compound of lead carbonate 
and lead hydrate. A perfectly finished White Lead con- 
tains two parts of lead carbonate and one part of lead 
hydrate (and nothing else), the former giving whiteness 
and the latter only hardening the oil ; but without it there 
is no paint, only a wash. Excess of lead hydrate lessens 
the opacity of the paint, too little lead hydrate lessens its 
binding power and working quality. One who has had 
ranch experience with White Lead writes : "The 'Strictly 
Pure,' as found in the market to-day, ground in oil, is a 
mechanical mixture of White Lead, acetate of lead, chem- 
ically pure carbonate of lead, partially corroded lead (in 
all stages of corrosion), rotten metallic lead, rotten tan- 
bark, and excess of water." 

"The Dutch Process of corroding lead is a 'happy-go- 
lucky' one." (Terry.) Under it a uniform product can- 
not be obtained, unless the pigment, after being taken 
from the stacks, is ripened and finished by alternate wash- 
ings and aerations until it is relieved from harmful in- 
gredients and excesses; for example, excess of water, lead 
acetate, lead carbonate, etc. Time and money only can 
accomplish this result. "The time is probably quickly 
coming when, except for indoor or the commonest pur- 
poses. White Lead Oil Paint; that is, White Lead ground 
in oil, with perhaps some linseed oil, turpentine, and 



38 A Handbook fo'' Paint-Users 

little dryers, will cease to be used for any engineering 
structure except of the meanest kind." — (JVewman.) 

Zinc White. — Zinc white, or the oxide of zinc, has been 
recently attracting attention. The action of the French 
Government in requiring its use upon all public structures 
in preference to White Lead has doubtless, in a large 
measure, brought this about; however, it is a dangerous 
pigment to use, because, when mulled with linseed oil, 
brittle soap seems to be formed, which causes a paint 
made from it to lack adhesiveness, and peel or scale off. 
Then, again, if a dried film of paint made from it is ex- 
posed to the action of carbonic acid and water, more or 
less of the zinc oxide is converted in time into zinc car- 
bonate, which is more obviously crystalline and more 
bulky than the oxide; therefore, such a paint would lose 
its hiding power, and increase in volume, causing motion 
in the dried paint. The remedy for the defects in zmc 
oxide is to alloy it with other pigments that will im- 
prove it. 

The varieties of zinc oxide sold are of two essential 
kinds : First, that from the oxidation of metallic zinc; 
second, that obtained from the sublimation of zinc ores. 
The former are more dense and better paint pigments than 
the latter. (Occluded gases.) 

The particles of zinc oxide are "needle-formed," like 
snow. The objectionable features in oxide of zinc may be 
largely overcome by tempering and combining it with lead 
products, oxides of iron, carbon, or any hard, indifferent 
powder. 

Inert Matter. — An important function of the solids in 
paint is to protect the dried binder from destructive in- 
fluences. Some substances, by virtue of their stable 
nature, possess this property in a high degree. They do 



A Handbook for Paint-Users 39 

not act chemically upon the oil, and are not easily 
changed. They are classed as inert pigments, and should 
be used simply as a means of improving and increasing 
the durability of the paint. 

" How many metals make the bronze of Corinth ? " 

Pigvient Alloys. — Regardless of color, there is no one 
pigment that will "answer all the requirements, fill all tlie 
oflBces," of a perfect pigment to mix with linseed oil for 
paintmaking; not a single pigment that will do what pig- 
ment must do, until a better medium is found for paint- 
making than linseed oil; namely, "take and retain the 
binder, cover and obscure the surface," prolong the life of 
the oil, and make it dry fast enough for practical use. 
Certain solids, under certain conditions and in certain pro- 
portions, have mutual action upon each other; they inter- 
change elements and combine to form new substances, 
just as metals alloy and form new metals. Now, apply- 
ing this truth to pigments : In order that chemical 
combination may follow, or that that which is bad in one 
pigment may be linked with that which is bad in another, 
to produce a new pigment that is good, it is necessary 
that the solids under consideration be very finely divided, 
very closely intermingled; and that the affinity between 
them be great enough to excite the desired interchanges 
and to form the new substance. 

It is upon this sound theory that most combination 
paints are unwittingly made. If such paints are scientif- 
ically and honestly made, they are worthy of the utmost 
confidence, and we think they will ultimately displace all 
others. 



TESTS 

"Prove all things, hold fast that which is good." 

PAINT tests may be of three kinds ; namely, Chemical, 
Mechanical, and Physical tests. 

Chemical Tests. — In the selection of solids and liquids 
for paintmaking, it is well to know that they contain no 
deleterious matter, such as soluble solids or destructive 
liquids, nor useless substances either to make weight or 
to make bulk. Chemistry can tell these things, but it 
cannot tell the quality of the bulk of paint materials used. 
"Chemistry is physics applied to atoms and molecules." 
(Tyndall.) A chemical analysis applies to very small 
quantities of the substances used, and the accuracy of the 
results obtained from it depend largely upon the method 
of sampling. When one considers that about all pigments 
are allotropic, that no two lots of paint liquids are exactly 
alike, and that any prepared paint changes more or less, 
in one way or another, with age, the chemist's test is 
proved to be of value in so far as it relates to the matter 
subject to his analysis and determinations, and no further. 

The popular idea of a chemist is that of one who can 
analyze material substances and determine their composi- 
tion — that is, take them apart ; the main study of the 
progressive paintmaker of to-day is synthetic chemistry 
— that is, combining separate substances into new forms. 
Chemistry can tell things that may have been used in 
making a paint ; it can foretell some phenomena that it 
may develop, but it cannot at all surely predict its "vis 
viva" — that is, what the stuff will do, and what it will 
do is the only true measure of its value or worth. "Chem- 

40 



A Handbook for Paint-Users 41 

istry is the science of affinity. " (Simon.) "Essentially 
heterogeneous bodies excite chemical affinity." Do you 
fancy that a chemist can probably know the affinities that 
exist in the kinds of gross matter used by the paintmaker 
as well as the paintmaker can ? The solids and liquids 
used to secure a worthy paint must have a liking for one 
another, else you cannot get a fairly homogeneous liquid 
mass ; if you do not get that, you have a poor paint. 
Further, the quality of paint depends quite as much upon 
its physical as it does upon its chemical properties. 

Mechanical Tests. — By this is meant tests made by a 
skillful painter. No one can determine the working 
qualities of paint as well as the man whose eye and hand 
and arm are trained through practice. The importance 
of the proper application of paint receives less attention 
than it deserves, e. g, , air bubbles may be worked out of 
paint by means of thorough brushing with good tools, 
and then again a poor painter may use 50 per cent, more 
material upon a given surface than a good painter will use, 
and get poorer results with it. Engineers and architects 
should demand the employment of competent artisans to 
do their painting, for results are often more dependent 
upon the intelligence and good will of the painter than 
upon the quality of the material used. 

It is worthy of mention that in all the years the com- 
pany with which the author has been connected has been 
making tests of paints upon roofs, bridges, and test-plates 
of wood, iron, steel, and glass, while of course results 
have often been non-concordant and we have noted great 
difference in durability, covering, working, and drying 
properties, yet we have never had the paint blister, scale, 
or peel off. Why ? Because each coat has been applied 
by an expert painter with thought and care, to a surface 



42 A Handbook for Paint-Users 

in fit condition to receive it, and the paint was, in each 
instance, protected when drying. 

Physical Tests. — By this is meant weather tests, or the 
exposure of the dried paint, on metallic or other surfaces, 
to the destructive forces of nature, such as sunshine, rain- 
fall, frost, dew, heat, cold, light, darkness, etc., or to 
those agencies which are frequently present in atmospheric 
air, that shorten the life of dried paint, such as acid or 
alkaline gases and vapors. Comparative tests on limited 
surfaces — that is, small plates of steel or glass — are often 
misleading, because a painter cannot gauge his work with 
unfamiliar material, and because his brush probably will 
not be in condition to give the paint a fair show. In order 
to make such tests more reliable, they should be re- 
peated a number of times to note if results are concord- 
ant ; and large sizes of plates should be used, as recom- 
mended by the American Society for Testing Materials, 
say ^" X 20" x 24" prepared in pairs, "one to be exposed 
green and the other to be thoroughly dried under favora- 
ble conditions previous to exposure." 

Actual service tests under normal conditions give the 
most conclusive data to guide us, but so long as it takes 
years to make them, common sense dictates that consum- 
ers should hold fast to materials that universal experience 
has proven trustworthy until better are found. Acceler- 
ated tests under "abnormally severe conditions" have 
little value unless "the results obtained by the method 
selected will be in harmony with long time service tests." 
It is easy to test the water-proofing quality of a dried 
coating of paint, but such a test determines nothing more 
than the ability of the paint to exclude water from the 
surface underneath it. It is easy to test the effect of arti- 
ficial heat upon dried paint, but this does not determine 



A Handbook for Paint- Users 43 

the power of the paint to withstand sunshine. We have 
found no quick test to determine the probable Hfe of paint, 
under given conditions, but are led to conclude that one 
intimately acquainted with the properties of the subject- 
matter, and with the forces of nature, may reasonably 
predict its life, if he knows the method of application, 
the conditions under which it is to be exposed, and the 
condition of the surface upon which it is to be applied. 



CONCLUSION 

"Facts are nothing, but the ideas they signify, the analogies 

that they evoke, eire everything." 

—Jean Morcas. 

GUIDED by study of the phenomena pertaining to the 
subject matter, — that is, oil paint, — and reasoning 
by analogy and inference from practice and experiments, 
at the present time, the following conclusions have been 
reached in regard to structural steel coatings: 

1. That the surface of steel must be in fit condition to 
receive paint, provided a worthy paint is used; otherwise, 
it is better to use a cheap paint or tar preparation. 

2. That to know the probable results to be obtained 
from the use of any paint materials, one must know the 
following things about them; namely: 

A — Their history and mode of preparation. 
B — Their physical properties. 
C — Their chemical properties. 

3. That a competent paintmaker can design a paint to 
meet any reasonable conditions of location, atmosphere, 
temperature, surface, application, drying, and wear, but 
that in order to do so he must know the conditions; that 
these being known he should be entrusted with the manu- 
facture of a coating to accomplish the results desired. 

4. That the priming, or first coat of paint, upon any 
surface, is the most important one, and that it should 
form a firm and unyielding foundation for those to fol- 
low it. 

44 



A Handbook for Paint- Users 45 

5. That under-coats should dry harder and more 
quickly than those above them, and that the difference in 
drying between adjoining coats should not be very great. 

6. That the quality of the binder is equally as impor- 
tant as the quality of the pigment. 

7. That the quantity or weight of pigment used is 
equally as important as its quality or volume. 

8. That the method of application is equally as impor- 
tant as the quality of the paint. 

9. That no accelerated tests can be the equivalent of 
a long-time service test. 

! Theory is practice applied to atoms and mole- 
cules. 
Practice is theory applied to masses. 



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